Alkyl sulfoxide detergent



United States Patent Ofifice 3,243,453 Patented Mar. 29, 1966 3,243,463ALKYL SULFOXIDE DETERGENT William von E. Doering, New Haven, Conn.,assignor to The Procter & Gamble Company, Cincinnati, Ohio, acorporation of Ohio N Drawing. Filed Nov. 14, 1962, Ser. No. 237,716

5 Ciaims. (Cl. 260-607) This invention relates to novel1,3-bis-sulfoxides and detergent compositions containing them.

In constant improvement of organic detergent compounds certain featureshave been found to be highly desirable. These features includeresistance toward the ingredients imparting hardness to Water and 'ahigh degree of detergency. Although there are a number of organicdetergent compounds which have these characteristics, detergentcompounds having additional desirable characteristics find a wider scopeof application.

US. Patent 2,658,038, Wayne A. Proell, describes a class of1,2-bis-sulfoxide detergent compounds which are relatively mild to theskin and which have eifective detergency characteristics. These1,2-bis-sulfoxides have the where R is a lower alkyl R is an alkylcontaining 6 to 20 carbon atoms and R" is H or lower alkyl. Attempts toformulate these 1,2-bis-sulfoxide compounds into detergent compositionscontaining alkaline builder materials (for the purpose of enhancing thedetergency of the 1,2 bis-sulfoxide detergent compounds) showed that the1,2- bis-sulfoxides are subject to decomposition in the presence of suchalkaline materials. Apparently, the presence of an alkaline materialcatalyzes the decomposition of a 1,2-bis-sulfoxide into odoriferousproducts (e.g., methyl disulfide), thereby reducing the effective amountof detergent and creating a severe odor problem. Moreover, the1,2-bis-sulfoxides have poor thermal stability and odoriferousdecomposition products are formed at elevated temperatures, such asthose encountered during transit and storage of detergent compositions,particularly in the presence of moisture, and during heat dryingoperations. These decomposition problems indicated that bis-sulfoxideswould generally be unsuitable for alkaline built detergent compositions,particularly heatdried compositions.

It is an object of this invention to provide novel bissulfoxidedetergent compounds having high degrees of detergency, thermal stabilityand stability in an alkaline environment. It is a further object of thisinvention to provide built detergent compositions containing suchbissulfoxide compounds.

It was found that these and other objects are achieved in a novel classof 1,3-bis-sulfoxides having the structure set forth below and inalkaline detergent compositions containing such compounds, which have asurprising al kaline and thermal stability, as hereinafter more fullydescribed.

wherein one R is an alkyl group containing from about 8 to about 16carbon atoms, preferably in a straight chain, and the other R ishydrogen; R is a methyl or ethyl group or hydrogen; R and R are methylor ethyl groups. Preferably R and R are methyl. The class of compoundsdescribed will hereinafter be referred to more simply as1,3-bis-sulfoxides. For convenience the bissulfoxides in which the longchain alkyl group is located midway between the alkylsulfinylsubstituents are designated as symmetrical 1,3-bis-su1foxides; where thelong chain alkyl group is located on a carbon bearing an alkylsulfinylgroup, the bis-sulfoxides are designated unsymmetrical1,3-bis-sulfoxides. The preferred symmetrical 1,3-bis-sulfoxides are2-alkyl-l,3-bis(methylsulfinyl) propanes; the preferred unsymmetrical1,3-bis-sulfoxides are 1-alkyl-l,3-bis(methylsulfinyl) propanes; in bothcases the alkyl ranges from about 8 to about 16 carbon atoms. Examplesof the compounds of this invention are:

2-decyl-l,3-bis(methylsulfinyl) propane 2-tetradecyl-1,3-bis(methylsulfinyl) propane 2-hexadecyl-1,3 -bis (methylsulfinyl) propane1,3-bis(methylsulfinyl) pentadecane (or l-dodecyl-1,3-bis(methylsulfinyl) propane) 2-dodecyl-1,3 -bis (ethylsulfinyl) propane2-dodecyl-l,3-bis(methylsulfinyl) butane (or l-methyl-Z-dodecyl-1,3-bis(methylsulfinyl) propane)Z-tetradecyl-l-(methylsulfinyl)-3-(ethylsulfinyl) pentane (orl-ethyl-2-tetradecyl-l- (ethylsulfinyl) -3-(methylsulfinyl) propane)2-dodecy1-l,3-bis(methylsulfinyl) propane is a preferred compound ofthis invention because of its optimum detergency characteristics, inboth Warm and cool water.

In general, the 1,3-bis-sulfoxides of this invention can be prepared bysynthetic methods involving the following steps:

(1) The preparation of 2-alkyl-1,3-propanediol by reduction of thecorresponding lower alkyl malonate ester, e.g., diethyl-2-alkylmalonate.

(2) Conversion of the 2-alkyl-l,3-propanediol by phosphorus tribromideor hydrobromic acid to the 2-alkyl-1,3- dibromopropane.

(3) Replacement of the 1,3-dibromo groups by methylmercapto groups byreaction of the 2-alkyl-1,3-dibrom-opropane with alkali metal (e.g.,sodium) methyl mercaptide.

(4) Oxidation of the 2-alkyl-1,3-bis(methylmercapto) propane.

(Alkyl in the above steps ranges from C to C By the use of appropriate1,3-diols having an unsymmetrical structure the correspondingunsymmetrical 1,3- bis-sulfoxides can be prepared. For example,1,3-alkanediols can be obtained by reduction of long-chain ,B-ketoesters. These can serve as starting material for the synthesis ofunsymmetrical 1,3-bis-sulfoxides by steps similar to those outlined forthe symmetrical compounds.

Alternate routes for preparation of the 1,3-bis-sulfoxides exist andwill occur to those skilled in the art after reading the presentdescription.

In 1,3-bis-sulfoxides of this invention, R can be derived from naturallyoccurring fats and oils or from synthetic sources. Mixtures of1,3-bis-sulfoxides are quite suitable wherein the R groups vary in chainlength in the C to C range, as for example, the alkyl groups fromcoconut fatty alcohol or distilled coconut fatty alcoho The1,3-bis-sulfoxides of this invention are useful per se as detergent andsurface active compounds. The uses to which surface active compounds canbe put are numerous and well known, e.g., preparing oil-in-wateremulsions, textile treating, dyeing, flotation, preparation of rubberlatex, and the like. Desirably the 1,3-bis-sulfoxides are used withalkaline builder materials to form built detergent compositions, as forexample, liquid, bar, flake, granular or tabletted granularcompositions. Such compositions have enhanced detergency characteristicsdue to the coaction in aqueous washing solution between the ethyleneoxide.

1,3-bis-sulfoxides and the alkaline builder material. It is in such analkaline medium that the surprising and advantageous usefulness of the1,3-bis-sulfoxides, i.e., superior stability in the presence of alkalinematerials, is best demonstrated. Preferably the alkaline builder in suchdetergent compositions is a material selected from the class consistingof water soluble inorganic alkaline builder salts, water soluble organicalkaline sequestering builder salts and mixtures thereof. Desirably theratio of 1,3-bis-sulfoxide to the alkaline builder material is in therange of about 4:1 to about 1:20. (Parts, ratios and percentages hereinare by weight.) Preferably the alkaline builder material should providea pH of about 8 to about 11 when the detergent composition is dissolvedin water.

Water-soluble inorganic alkaline builder salts used alone or inadmixture are alkali metal carbonates, borates, phosphates,polyphosphates, bicarbonates and silicates. (Ammonium or substitutedammonium builder salts, e.g., tri-ethanolamine, can also be used.)Specific examples of such salts are sodium tripolyphosphate, sodiumcarbonate, potassium carbonate, sodium tetraborate, sodiumpyrophosphate, potassium pyrophosphate, sodium bicarbonate, potassiumtripolyphosphate, sodium haxametaphosphate, sodium sesquicarbonate,sodium monoand di-ortho phosphate and potassium bicarbonate. organicbuilder salts enhance the detergency of the subject 1,3-bis-su1foxides.

Examples of organic alkaline sequestrant builder salts used alone or inadmixture to enhance detergency are alkali metal, ammonium orsubstituted ammonium, aminopolycarboxylates, e.g., sodium and potassiumethylenediaminetetraacetate, sodium and potassiumN-(2-hydroxyethyl)-ethylenediaminetriacetates, sodium and potassiumnitrilotriacetates and sodium, potassium and triethanolammonium N-(2-hydroxyethyl -nitrilodiacetates. Mixed salts of thesepolycarboxylates are also suitable. The alkali metal salts of phyticacid, e.g., sodium phytate are also suitable as organic alkalinesequestrant builder salts (see US. Patent 2,739,942). Also suitable arethe water soluble salts of ethane-1-hydr0xy-1,1-diphosph0- nate, e.g.,the trisodium and tripotassium salts.

The detergent compositions of this invention can contain any of theusual adjuvants, diluents and additives, for example, anionic, nonionic,ampholytic, cationic or zwitterionic detergents, perfumes,anti-tarnishing agents, anti-redeposition agents, bacteriostatic agents,dyes, fluorescers, suds builders, suds depressors, and the like Withoutdetracting from the advantageous properties of the compositions.Examples of anionic detergents are sodium coconut soap, sodiumdodecylbenzene sulfonate and potassium tallow alkyl sulfate. Examples ofnonionic detergents are dodecyldimethylamine oxide and the condensationproduct of coconut fatty alcohol with 5.5 moles of An example of azwitterionic detergent is 3(N,N-dimethyl-N-hexadecylammonio)-2-hydroxypropane-l-sulfonate. Anexample of an ampholytic detergent is sodium-3-dodecylaminopropionate.An example of an alkaline-compatible cationic detergent isdodecylmethylbenzyl sulfoxonium methosulfate.

Following are examples which illustrate the 1,3-bissulfoxide compoundsand compositions of this invention. There are of course, modificationsof these illustrations which can be made by those skilled in the artwithout departing from the scope of this invention as defined in theappended claims.

EXAMPLE I A. Preparation of diethyl Z-dodecylmalonate To 50.6 g. ofsodium (2.2 moles) dissolved in 1600 ml. of absolute ethyl alcohol wasadded 352 g. (2.2 moles) of diethyl malonate, with stirring at roomtemperature. To the resulting solution was added, dropwise withstirring, 548 g. (2.2 moles) of dodecyl bromide. After addition Such in-I cap-tan.

" 180 C. for 4 hours.

pane was 152.5 g. (82.5%).

was complete, the mixture was refluxed and stirred for 5 hours andallowed to stand overnight. The mixture was made neutral by theadditionof glacial acetic acid. The inorganic salts were filtered offand the alcohol solvent was removed by distillation. After washing theresidue three times with water and drying the organic layer over sodiumsulfate, the residue was distilled through a helicespacked column. Thefraction boiling at 137142 C. at 4.7 mm. of mercury was collected. Thediethyl Z-dodecylmalonate thus obtained weighed 484 g. and hadrefractive index n :1.4400 (yield 67%). f

B. Reduction of diethyl Z-dodecylmalonate to Z-dodecyl-I,3-pr0panediolTo a slurry of 35 g. of lithium aluminum hydride in 1500 cc. of drytetrahydrofurane was added 251 g. of diethyl 2-dodecylmalonate (0.76mole). Addition was dropwise with stirring and at a rate to giverefluxing of the solvent. After addition was complete the mixture wasrefluxed and stirred for 1 hour. Ethyl acetate was added to the reactionmixture to decompose the excess lithium aluminum hydride. Then aqueous10% sulfuric acid was added cautiously and the mixture stirred untillayers could be separated. The tetrahydrofurane layer was separated andcooled in a Dry-Ice bath'yielding 149 g. of crude2-dodecyl-1,3-propanediol. A single recrystallization from hexane gave130 g. (71% yield) of the desired 2-dodecyl-1,3-propanediol melting at7071 C.

C. Preparation of Z-dodecyl-I,S-dibromopropane stirring. The diol, asolid, gradually went into solution as the bromide was added, and thereaction became exothermic. The temperature rose early in the reactionto 170 C. then was reduced to 135 C. by cooling and held there for 24hours. The temperature was then raised to Finely cracked ice and waterwere added to the reaction mixture and the mixture transferred to aseparatory funnel and extracted with ether. The ether layers werecombined with the organic layer and the, combined solutions extractedwith sodium carbonate solution followed by water washing. The etherealsolutions were dried over sodium sulfate, the ether evaporated, and theresidue distilled through a short distilling column. Yield of thedesired 2-a1kyl-1,3-dibromopro- The product boiled at 144- 146 C. at 0.4mm. mercury and had refractive index n =1.4857.

D. Preparation of 2-dodecyl-1,3-bis- (methylmercapto) propane Sodiumhydroxide (56 g.) was dissolved in 80 ml. of water and 800 ml. ofethanol was added. The mixture was cooled to room temperature and heldthere by cooling during the addition of 63 g. (1.25 moles) of methylmer- After addition of the methyl mercaptan to the basic solution wascomplete, 152 g. (0.41 mole) of 2- dodecyl-1,3-dibromopropane was addeddropwise at room temperature. The mixture was raised to refluxtemperature and refluxed with stirring for 4 hours. The mixture was thenpoured into 4 liters of water and the organic phase separated. Theaqueous phase was extracted with ether and the ether extract combinedwith the organic phase. The combined ethereal solutions were Washed withwater, dried over calcium chloride, and the ether evaporated. Theresulting 112 g. of crude product was distilled through a short Vigreuxcolumn yielding 108 g.

of the desired 2-dodecyl-1,3-bis(methylmercapto) propane boiling at 156C. at 0.45 mm. of mercury. Refractive index n =1.4868. Density d=0.9087.

B. Preparation of Z-dodecyl-1,3-bis(methylsulfinyl) propane2-dodecyl-1,3-bis(methylmercapto) propane ('108 g., 0.355 mole) wasdissolved in 1000 ml. of ethanol. To the resulting solution was added,dropwise with stirring (and cooling to maintain the temperature below 35C.), 95 g. (0.82. mole) of 30% aqueous hydrogen peroxide. After thematerials were mixed they were stirred for 1 hour until homogeneous andallowed to stand overnight. Palladium-charcoal catalyst was added to thereaction mixture, and the aqueous alcohol solvent was removed in vacuoThe combined solids were dissolved in hot acetone and filtered to removethe palladium catalyst. The filtrate was made up to about 1 liter withhot acetone, 500 ml. of hexane was added and the hot mixture cooledslowly to room temperature and filtered. The filter cake, 2-dodecyl-1,3-bis(methylsulfinyl) propane weighed 78.5 g. (66%) and melted at116.5117.5 C. Analyses of this product gave sulfur=18.81%;carbon=60.82%; and hydrogen: 10.55%. (Theory for the product:sulfur=19.05%; carbon=60.71%; and hydrogen=10.7l%.)

Built laundry detergent compositions containing 50% sodiumtripo-lyphosphate, 30% sodium sulfate and 20%2-dodecyl-l,3-bis(methylsulfinyl) propane, resulted in lipid .soildetergency properties (using naturally soiled cloth and wash water at140 F.) superior to like formulations containing sodium dodecyl benzenesulfonate and approaching like formulations containing sodium tallowalkyl sulfate. The 1,3-bis-sulfoxide was superior to both thedodecylbenzenesu lfonate and the tallow alkyl sulfate in wash water at80 F. As regards detergency, 1,3-bissulfoxides are at least as effectivein built compositions as 1,2-bis-sulfoxide in built compositions(freshly prepared) containing, respectively, the same long chain alkylgroups.

As determined by guinea pig mildness tests, the l,3-bissulfoxides ofthis invention, e.g., Z-dOdecyI-LS-bis- (methylsulfinyl) propane arevery mild to the skin. Such guinea pig tests are described in CanadianPatent 639,398 issued April 3, 1962, to Howard F. Drew et al.

1,3-bis-sulfoxides, e.g., Z-dodecyl-1,3-bis(methylsulfinyl) propane, canbe used per se as detergents for hand washing or washing of woolens inaqueous solutions of 1% concentration for example.

The symmetrical 1,3-bis-sulfoxides differ markedly in solubilitycharacteristics from corresponding 1,2-bissulfoxides. Unlike the1,2-bis-sulfoxides, the symmetrical 1,3-bis-sulfoxides exhibit extremelysteep Krafit ranges. This permits the use of water as arecrystallization solvent. The unsymmetrical 1,3-bis-sulfoxides, e.g.1,3-bis(rnethylsulfinyl) pentadecane, are more soluble than thecorresponding symmetrical compounds.

As to bacteriostatic activity, 2-dodecyl-1,3-bis(methylsulfinyl) propaneeffectively controlled M. aareas at 4.7 p.p.rn. and E. coli at about 150p.p.m., being superior in this respect to 1,2-bis-sulfoxides.

To test the alkaline stability of the 1,3-bis-sulfoxides of thisinvention, particularly as compared to 1,2-bis sulfoxides, 8% aqueoussolutions of potassium pyrophosphate were used. A series of samplescontaining 3 grams of 2-dodecyl-1,3-bis(methylsulfinyl) propane in 150ml. of the pyrophosphate solution was compared with a like series of 3grams of l,2-bis(met-hylsulfinyl) tetradecane in 150 ml. of thepyrophosphate solution. (The difference of one methylene group in thesamples was found to be not significant for purposes of the comparison.)The solutions were kept at 60 C. and pH 10. A slow stream of nitrogenwas used to sweep volatile products into traps containing 3% aqueousmercuric chloride. Periodically the precipitated c'omplex of methyldisulfide with mercuric chloride which formed in the traps was removed,dried and weighed to assess the rates of formation of decompositionproducts. In 14 days the 1,3-bis-sulfoxide produced no precipitate. The1,2-bis-sulfoxide produced 0.6 gram of precipitate inl day, 1.0 gram in5 days and 1.1 grams in 12 days. At this point, decomposition of the1,2-bis-sulfoxide was substantially complete. This demonstrated thesurprising alkaline stability of the 1,3- bis-sulfoxide as compared tothe 1,2-bis-sulfoxide.

Samples of 2-dodecyl-l,3-bis(methylsultfinyl) propane remained odor-freeon storage at room temperature for three months. 'The odor ofdecomposition products is quite noticeable in sealed samples of1,2-bis-(methylsulfinyl) tetradecane in a few days. A sample of this1,3-bis-sulfoxide was heated in vacuo for seven hours at C. (with verylittle decomposition. A sample of this 1,2-bis-sulfoxide, however,completely decomposed in four hours upon heating in vacuo at 150 C. The1,3- bis-sulfoxides of this invention, e.g., 2-dodecyl-l,3-bis-(met-hylsul-finyl) propane, show similar superior thermal stabilitycharacteristics over 1,l-bis-sulfoxides, e.g., 1,1- bis (methylsulfinyl)dodecane.

The 1,3-bis-sulfoxides of this invention can be used in efiectivealkaline detergent compositions having the following formulations.

Granular detergent:

Percent Z-dodecyl-l,3-bis(methylsulfinyl) propane 10 Sodiumdodecylbenzene sulfonate (the dodecyl group being derived fromtetrapropylene) 10 Sodium tripolyphosphate 50 Sodium sulfate 30 Percent2-dodecyl-l,3-bis(ethylsulfiny1) propane 10 Condensation product of onemole of dodecanol and twelve moles of ethylene oxide 3 Sodiumpyrophosphate 57 Sodium carbonate 3 Trisodium phosphate 3 Sodium sulfate24 Liquid detergent:

Percent Z-decyl-l,3-bis(methylsulfinyl) butane 6 Sodium tetrapropylenebenzene sulfonate 6 Potassium pyrophosphate 10 Potassiumnitrilotriacetate 10 Potassium toluene sulfonate 8 Sodium silicate 3.8Carboxymethyl hydroxyethyl cellulose 0.3 Water Balance'2-tetradecyl-1,3-bis(methylsulfinyl) propane 5 Ethanol l0 Tetrosodiumethylenediaminetetraacetate 10 Water 75 What is claimed is: 1.1,3-bis-sulfoxide detergent compounds having the formula where one R isan alkyl group containing from 8 to 16 carbon atoms and the other R ishydrogen; R is selected from the group consisting of methyl and ethylgroups and hydrogen; R and R are selected from the group consisting ofmethyl and ethyl groups.

2 The compounds of claim 1 wherein R and R are methyl groups.

3. 2-alkyl-1,3-bis(methylsulfinyl) propane, wherein the alkyl rangesfrom about 8 to about 16 carbon atoms.

4. Z-dodecyl-l,3-bis(methylsulfinyl) propane.

5. la-lkyl-1,3-bis(methylsulfinyl) propane wherein the alkyl ranges fromabout 8 to about 16 carbon atoms.

(References on following page) References Cited by the Examiner UNITEDSTATES PATENTS Proe'll.

Webb 252-138 Sorensen 260-607 Tuvell 252-138 Schultz et a1 260-607 Comaet a1 260-607 OTHER REFERENCES Gaylord: Reduction With Complex MetalHydrides, 1956, page 418.

5 CHARLES B. PARKER, Primary Ey cam z'ner.

A. T. MEYERS, DELBERT R. PHILLIPS, Assistant Examiners.

1. 1,3-BIS-SULFOXIDE DETRGENT COMPOUNDS HAVING THE FORMULA